I'm brewing a sour, and it's been in primary for 4 weeks. Plan on racking it into a carboy for long term storage until the bugs are finished.

My question is this. I want to rack a new beer onto the old yeast. It's white labs belgium sour blend, which I believe contains yeast and bugs.

Is this a bad idea? Could the saccaromyces be dead but bugs alive, this tainting the new wort I plan to add?

Interesting question. I've racked on top of 1056 yeast a few times, works great. But I have no clue on the sour stuff.

I know the bugs will be fine, but I don't want to rack onto dead yeast. Maybe my window of opportunity is gone because one needs to rack within 2 weeks to avoid autolyzed yeast? I certainly don't know, but I hope someone does.

4 weeks isn't nearly long enough for autolysis to start so that shouldn't really be an issue (autolysis is an issue after many months). I think the main issue you'll have is that the blend of yeast and bugs will be much different in the slurry from the first batch since each strain would not necessarily have multiplied at the same rate. If it were me, I'd go for it since I'm always interested in answering those "what happens if" questions.

Interesting. Well, here is another thought... Can I add some wood chips and wort starter to a carboy and add this slurry. Let it sit a year or more and allow the bugs to do some serious work and harbor in the wood, then pull that wood out and use it in another beer?

Sounds like a good plan. If you think of it, you could reply to this same thread in a year or so to give an update as to how it worked out. Oftentimes threads like this will come along and the questions will appear to remain unanswered. Fortunately this forum allows for new posts to old topics so you can keep the question and your own answer all in the same place and we'll all benefit from your experience.

If you're going for a lambic-esque beer with puckering acidity and lots of funk, using slurry from a previous blend pitch is the way to go.

I pull a few pints of slurry and wash down the fermentor before dumping in the next batch. Otherwise you'll collect a LOT of trub/dead yeast over the course of a few batches on the same yeast.

Oak is nice in this type of beer. If it will be in there for awhile (and you want to harbor bugs in them) oak cubes are best. Wider breadth of oak flavors to contribute, more internal surface area for bugs to live.

If you're going for a lambic-esque beer with puckering acidity and lots of funk, using slurry from a previous blend pitch is the way to go.

I pull a few pints of slurry and wash down the fermentor before dumping in the next batch. Otherwise you'll collect a LOT of trub/dead yeast over the course of a few batches on the same yeast.

Oak is nice in this type of beer. If it will be in there for awhile (and you want to harbor bugs in them) oak cubes are best. Wider breadth of oak flavors to contribute, more internal surface area for bugs to live.

When you are talking slurry vs trub, how do make the distinction? I was just going to rack the beer off using the spigot and toss the next batch right in. How do you go a out separating the yeast slurry from trub?

If you're going for a lambic-esque beer with puckering acidity and lots of funk, using slurry from a previous blend pitch is the way to go.

I pull a few pints of slurry and wash down the fermentor before dumping in the next batch. Otherwise you'll collect a LOT of trub/dead yeast over the course of a few batches on the same yeast.

Oak is nice in this type of beer. If it will be in there for awhile (and you want to harbor bugs in them) oak cubes are best. Wider breadth of oak flavors to contribute, more internal surface area for bugs to live.

When you are talking slurry vs trub, how do make the distinction? I was just going to rack the beer off using the spigot and toss the next batch right in. How do you go a out separating the yeast slurry from trub?

I don't think he was suggesting separating yeast from trub. just scoop out a quart or so into a sanitized mason jar and then wash the fermenter.

If you're going for a lambic-esque beer with puckering acidity and lots of funk, using slurry from a previous blend pitch is the way to go.

I pull a few pints of slurry and wash down the fermentor before dumping in the next batch. Otherwise you'll collect a LOT of trub/dead yeast over the course of a few batches on the same yeast.

Oak is nice in this type of beer. If it will be in there for awhile (and you want to harbor bugs in them) oak cubes are best. Wider breadth of oak flavors to contribute, more internal surface area for bugs to live.

When you are talking slurry vs trub, how do make the distinction? I was just going to rack the beer off using the spigot and toss the next batch right in. How do you go a out separating the yeast slurry from trub?

I don't think he was suggesting separating yeast from trub. just scoop out a quart or so into a sanitized mason jar and then wash the fermenter.

Can you separate them? Or maybe should I toss some oak in now to harbor some bugs, let it sit a few more weeks, then take the oak and a quart or 2 of wort out. From what I understood from reading Vinnie C.'s AHA presentation, you can soak the wood in it water to kill the weak strains and let the strongest ones around.

Perhaps this is an option for propagation of bugs.

Guess this just went from reusing yeast to full blown experimental status.

Using oak as your only source of yeast/bacteria is another great option, but it provides a really low cell count. Its great for inoculating a primary-fermented beer with brett, but it wont give you the amount of yeast (sacch or brett) needed to ferment a batch of sweet wort.

With mixed ferments, you can wash slurry to remove trub/dead yeast, or you can just pour the next batch right on top of it. I've done both. It really just depends on how much trub you carry over and how many times you'll reuse the yeast.

You ARE kind of throwing caution to the wind with mixed fermentation, leaving your beer in the hands of the brett and bacteria. I think its fun, and if you brew quality wort, odds are good that it will develop into something special.